AIVDM & AIVDO NMEA sentence decoder
OpenSkipper Open Source C# code for Windows for integrating and displaying NMEA 0183, NMEA 2000 and AIS data from nautical instruments, GPS units and internet data sources, receive and transmit data over multiple connections, webserve to Laptop, Ipad or Android. by Dr Drew Mason and Jason Drake, updated in 2014 by Timo Lappalainen and Kave Oy from Finland.
NMEA Simulator 26.03.2019 NMEA Simulator can be used to simulate real devices on NMEA 0183 or NMEA 2000 bus. With simulator you can e.g. test you navigation software without real devices.
Sailsoft Freeware - WaypointCreator, IpaNmea, NmeaFileReader
Max Kagstrom Nmea Simulator -Free for a time
Labset Reed GPS Nmea Simulator
AIVDM/AIVDO protocol decoding Eric Raymond